The elimination of unwanted sounds and their distractive influence on the ear of the listener such as an individual in an office, conference room and the like, has been the subject of extensive efforts in the past and while many proposals for the elimination of such unwanted sounds have been made, no completely satisfactory solution has been arrived at to date. Such proposals have included the use of sound-proof construction for an enclosure which due to its cost have been relatively little used or the use of piped-in or canned music in an attempt to condition the environment to reject the unwanted sounds in the area occupied by the listener. However, music itself played continuously may become distracting to the listener or listeners over an extended period of time, particularly if the music is of a type which the listener may not find pleasing.
Recent efforts in the masking of unwanted sounds have been focused on the reaction of the human ear itself and it has been recognized that certain sounds may condition or desensitize the human ear so that it will naturally reject unwanted sound. However, such ear conditioning efforts have not met with any marked degree of success as either the sound generating apparatus has been too bulky and/or expensive or it does not act to reject all unwanted sounds or may in itself become a source of annoyance to the listener.